The present invention relates to devices employed in catheter guiding and exchanging procedures, and more particularly to guidewire and exchange wire interconnection apparatus.
Catheterization procedures, e.g. percutaneous transluminal angioplasty catheterization (PCTA), involve insertion of catheters into blood vessels and other body passageways. Frequently such passageways are convoluted, giving rise to difficulties in inserting the catheters. Accordingly, guidewires are employed to insure accurate positioning of body-inserted catheters.
More particularly, a guidewire is inserted and maneuvered along arterial or other passageways to the desired treatment site, leaving a proximal portion of the guidewire outside of the patient. Next, the catheter is threaded onto the guidewire proximal portion, which is received into a lumen formed in the catheter. The catheter is advanced over the guidewire, and thus guided to the desired treatment site. Typically the guidewire is at least slightly longer than the catheter, so that when the catheter is completely advanced to the treatment site, at least part of the guidewire proximal end portion protrudes from the catheter. For example, for a catheter length of 130 centimeters, the guidewire length can be about 150 centimeters.
Frequently in catheterization, the need arises to exchange catheters. Preferably the exchange is accomplished with the guidewire remaining in place, to avoid the need to maneuver yet another guidewire to the treatment site. An exchange requires gripping the guidewire proximal end portion to maintain its position while the catheter is removed in the proximal direction. However, well before the originally inserted catheter can be withdrawn in this manner, it completely covers the guidewire, and the physician or other user can not simultaneously maintain the guidewire and proximally move the catheter.
In view of this difficulty, the usual approach has been to remove the guidewire from the patient, leaving the originally inserted catheter in place to guide the advancement of an exchange wire to the treatment site. The exchange wire is substantially longer than the guidewire. The proximal portion of the exchange wire, remaining outside of the patient after complete insertion, is longer than the length of the catheter. Thus, the exchange wire can be maintained while the catheter is completely withdrawn from the patient. After a replacement catheter is inserted over the exchange wire, the exchange wire is removed and the guidewire reinserted.
The repeated advancing and withdrawing of guidewires and exchange wires presents undue risk of trauma to the blood vessels or other lumens, and increases the complexity and required time for the catheterization procedure.
Several guidewire and exchange wire coupling schemes have been proposed to avoid the need for the wire exchanges. For example, U.S. Pat. No. 4,917,103 (Gambale et al) and U.S. Pat. No. 4,922,923 (Gambale et al) disclose a guidewire and exchange wire interconnection system. A hollow tubular fitting is provided at the proximal end of the guidewire, while a reduced diameter tip is formed at the distal end of the exchange wire. With the distal tip inserted into the tube, the tube is crimped to form a permanent coupling of the wires.
U.S. Pat. No. 4,966,163 (Kraus et al) shows an extendable guidewire including a main section and an extension section. A releasable coupling of these sections is provided by an externally threaded male contact at the proximal end of the main section, and an internally threaded female contact at the distal end of the extension section. The female contact is mounted to rotate relative to the extension section.
Yet another coupling scheme is disclosed in U.S. Pat. No. 4,827,941 (Taylor et al). A guidewire assembly includes a main section with a reduced diameter undulating (sinusoidal) male contact at its proximal end. An extension section includes a tube at its distal end. The sinusoidal contact elastically deforms as it is inserted into the tube, to provide a friction fit. A similar approach is shown in U.S. Pat. No. 4,958,642 (Christian et al). Another friction fit approach is disclosed in U.S. Pat. No. 4,875,489 (Messner et al). A main section of an extendable guidewire has a tapered proximal end. An auxiliary section of the guidewire has a tube at its distal end. The tube has a longitudinal gap, and thus expands to receive the tapered end of the main section and resiliently retain the tapered end once inserted.
While the above approaches perhaps are an improvement as compared to multiple wire exchanges, each encounters difficulties, particularly in connection with smaller guidewires and exchange wires, which can have diameters as low as ten one-thousandths of an inch.
Therefore, it is an object of the present invention to provide a single device for performing the functions of the guidewire and the exchange wire in catheterization procedures.
Another object of the invention is to provide a simple and reliable means for releasably coupling a guidewire and an exchange section proximal to the guidewire.
A further object is to provide a guidewire/exchange wire system with separate guide and exchange sections releasably coupled to one another in a manner that prevents the transfer of torque from one section to the other.
Yet another object is to provide a guidewire with complementary contacts for coupling an exchange section to a guide section of the guidewire, in a manner that affords a tactile sense of completing the connection.